A Paleocene (Danian) marine osteoglossid (Teleostei, Osteoglossomorpha) from the Nuussuaq Basin of Greenland, with a brief review of Palaeogene marine bonytongue fishes

Abstract

The early Palaeogene represents a key interval in the evolution of modern marine fish faunas. Together with the first appearances of many familiar fish lineages characteristic of contemporary marine environments, early Palaeogene marine deposits worldwide feature the occurrence of osteoglossid bonytongues. Their presence in marine rocks is surprising, given that these fishes are strictly associated with freshwater environments in modern settings and in other parts of the fossil record. Despite its possible relevance to faunal recovery after the Cretaceous–Palaeogene (K–Pg) extinction, this marine osteoglossid radiation is relatively understudied. Here we describe an osteoglossid specimen from marine Danian deposits of western Greenland (Eqalulik Formation, northern Nuussuaq Peninsula). It consists of disarticulated cranial, pectoral and vertebral material belonging to a relatively large‐bodied predator, similar to the widespread †Brychaetus but with some distinctive features. This specimen expands the geographical range of extinct osteoglossids to the Arctic and represents one of the earliest records of this group in marine deposits. We review other fossil occurrences of marine osteoglossids, highlighting temporal and biogeographical patterns that characterize their rise, diversification and sudden disappearance in the middle Eocene. It is likely that the transition from freshwater to marine environments occurred around the K–Pg boundary, possibly related to ecological replacement of predatory fish lineages that went extinct at the end of the Cretaceous. Further study of the Eqalulik Formation fauna could yield additional insight into the consequences of the end‐Cretaceous extinction with regard to marine fish evolution and the assembly of modern marine faunas.

Offshore marine actinopterygian assemblages from the Maastrichtian–Paleogene of the Pindos Unit in Eurytania, Greece

“…Evidence available so far from the region ( Koch & Nicolaus, 1969 ), combined with our observations on ATD, are indicative of rather oligospecific faunas and low overall abundance of fossil individuals. This is congruent with the common motif of Paleocene non-otolith marine fish-bearing sites, which as a rule comprise poorly preserved, low diversity fossil fish assemblages (e.g., Adolfssen, Milàn & Friedman, 2017 ; Schwarzhans & Milàn, 2017 ; Capobianco, Foreman & Friedman, 2019 ; Solé et al, 2019 ; Taverne et al, 2019 ; for an exception see Alvarado-Ortega et al, 2015 ). Still the potential of ATD should be noted, as it yields identifiable material like the Eurytanian clupeid, which is so far the oldest known from the Tethys, followed by the much better-preserved clupeids from the Ypresian of Bolca, Italy ( Marramà & Carnevale, 2015a ; Marramà & Carnevale, 2015b ; Marramà & Carnevale, 2018 ).…”

“… References for the faunas: (1) English Chalk, southern England, U.K. ( Friedman et al, 2016 ); (2) Bearpaw Fm., St Mary River, Alberta, Canada ( Newbrey & Konishi, 2015 ); (3) Nardò, Italy ( Sorbini, 1981 ); (4) Pierre Shale Group, South Dakota, USA ( Parris, Smith-Grandstaff & Gallagher, 2007 ); (5) Mexcala Fm., Guerrero, Mexico ( Alvarado-Ortega et al, 2006 ); (6) Liburnica Fm., Trebiciano, Italy ( Bannikov & Sorbini, 2000 ; Carnevale & Johnson, 2015 ; Taverne, Capasso & Arbulla, 2019 ); (7) López de Bertodano Fm., Seymour Island, Antarctica ( Grande & Chatterjee, 1987 ; Cione et al, 2018 ); (8) Moroccan Phosphates ( Arambourg, 1952 ; Bardet et al, 2017 ); (9) Saldeño Fm., Mendoza, Argentina ( López-Arbarello, Arratia & Tunik, 2003 ); (10) “Type Maastrichtia”, Netherlands ( Friedman, 2012 ); (11) Harrana, Jordan ( Kaddumi, 2009 ; Lindgren, Kaddumi & Polcyn, 2013 ); (12) Pindos Unit, Gavdos Island, Greece (Cavin et al, 2012); (13) Pindos Unit, Eurytania, Greece ( Koch & Nicolaus, 1969 ; this work); (14) Mont-Aimé, Champagne, France ( Priem, 1898 ; Priem, 1908 ; Montenat et al, 2018 ); (15) Tenejapa-Lacandón Unit, Palenque, Chiapas, Mexico ( Alvarado-Ortega et al, 2015 ); (16) Eqaluik Fm., Kangilia, Greenland ( Capobianco, Foreman & Friedman, 2019 ); (17) Stevns Klint and København Limestone Fms., Stevns Klint and Faxe, Denmark/Limhamn, Sweden ( Adolfssen, Milàn & Friedman, 2017 ); (18) Landana, Cabinda, Angola ( Solé et al, 2019 ; Taverne et al, 2019 ); (19) Máncora Fm., Negritos, Peru ( Friedman & Johnson, 2005 ); (20) Fur Fm., Stolle Klint Clay, Jutland, Denmark ( Bonde, 1997 ); (21) Danatina Fm., Turkmenistan ( Bannikov, 1993 ); (22) Abazinka Fm., Gerpegezh, Kabardino-Balkaria, Russia ( Bannikov & Carnevale, 2012 ; Bannikov et al, 2017 ). Dotted lines represent weakly supported temporal range extensions.…”

“…Marine ray-finned fish (Actinopterygii) communities—especially pelagic ones—were heavily restructured by this extinction event, with many long-lasting lineages (e.g., †pachycormids, †ichthyodectiforms, epipelagic aulopiforms) selectively meeting their end, or becoming decimated, at, or near, the end of the Cretaceous ( Cavin, 2002 ; Friedman, 2009 ; Friedman et al, 2010 ; Sibert & Norris, 2015 ; Guinot & Cavin, 2016 ). At the same time, the ecological space freed by the K–Pg Extinction is thought to have enabled the staged ecological diversification of phylogenetically disparate lineages during the Paleogene, and the subsequent dominance of the hyper-diverse acanthomorph teleosts in pelagic marine habitats ( Friedman, 2010 ; Near et al, 2012 ; Miya et al, 2013 ; Near et al, 2013 ; Betancur-R, Ortí & Pyron, 2015 ; Guinot & Cavin, 2016 ; Alfaro et al, 2018 ; Capobianco, Foreman & Friedman, 2019 ; Friedman et al, 2019 ; Capobianco et al, 2020 ). Such trends become apparent in broad overviews of the Cretaceous–Paleogene fossil record of actinopterygians ( Cavin, 2002 ; Friedman, 2009 ; Guinot & Cavin, 2016 ), and receive further support from implications of molecular time scales ( Near et al, 2012 ; Near et al, 2013 ; Betancur-R, Ortí & Pyron, 2015 ; Alfaro et al, 2018 ; Friedman et al, 2019 ), or ichthyolith ( Arambourg, 1952 ; Becker, Mallery & Chamberlain, 2010 ; Sibert, Hull & Norris, 2014 ; Sibert & Norris, 2015 ) and otolith data ( Schwarzhans, 1996 , 2004 ; Schwarzhans & Milàn, 2017 ).…”

Large-bodied sabre-toothed anchovies reveal unanticipated ecological diversity in early Palaeogene teleosts

“…The most conspicuous example is a radiation of osteoglossids, a group that in the modern day is restricted to freshwater settings. Marine osteoglossids range in age from early Palaeocene (Danian) to middle Eocene (Lutetian) and include several named genera and unnamed forms [14,75]. Marine osteoglossids partially overlapped temporally, and in some cases co-occurred with, an early Eocene (Ypresian) to early Oligocene (Rupelian) shallow-water lineage of large-bodied (ca 1 m) paralepidid aulopiforms (barracudinas), a group that in the modern day is associated with meso-or bathypelagic settings [15].…”

“…All of these examples belong to a group of fishes called acanthomorphs, or spiny-rayed teleosts, which represent the dominant fish group in marine settings since the beginning of the Cenozoic [1,2]. However, the hypothesis that opportunity arising from the K/Pg extinctions fuelled diversification predicts that other groups may have also experimented with new roles in the early Palaeogene, although this has been little investigated (but see [14,15]) despite its significance for understanding the structure of marine faunas at that time.…”